Magnetic and structural studies of copper-lanthanoid complexes; The synthesis and structures of new Cu(3)Ln complexes of 6-chloro-2-pyridone (Ln=Gd, Dy and Er) and magnetic studies on Cu2Gd2, Cu4Gd2 and Cu3Gd complexes

The synthesis and structural characterisation of three copper-lanthanoid complexes are reported. The compounds, of general formula [Cu(3)M(chp)(8)-(NO3)(S)][M = Gd, S = H2O in 2; M = Dy, S = H2O in 3; M = Er, S = (H2O)(0.5)(MeOH)(0.5) in 4; chp = anion of 6-chloro-2-pyridone], are made by reaction of [Cu-2(chp)(4)] (1) with the hydrated lanthanoid nitrate salt in methanol. Structural studies reveal the three copper atoms lie in an approximate hemisphere about a central lanthanoid atom. Magnetic studies on 2 and two further Cu-Gd complexes show ferromagnetic coupling between the 3d and 4f metals. Consideration of these results along with magnetic data previously reported for Cu-Gd compounds leads to a correlation between the magnitude of this exchange coupling and the exponential of the Cu ... Gd distance. This is the first magneto-structural correlation reported for mixed d-block/f-block metal complexes.